WASET
    Soma Roychowdhury,  A Multi-period Profit Maximization Policy for a Stochastic Demand Inventory System with Upward Substitution.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    September 2009, vol. 33(9). 762 - 770
    [viewed 20 April 2024]. Available from: https://publications.waset.org/pdf/8021.